i gruppi di pressurizzazione gp gp pressure booster sets groupes de ...

electric panel by means of suitably calibrated pressure
switches. Drawing water from the connected system, when
the pumps are stopped, causes lowering of the pressure
and the consequent making of the contact of the pressure
switch with the highest calibration value which causes
starting of the first pump (or pilot pump for 2+1GP or
3+1GP sets). If the pressure drop continues or restoring is
not sufficient, the second pressure switch intervenes and so
the second pump starts, and so on if the set is provided
with a third and fourth pump (main pumps). The restoring
of the pressure in the system causes the making of the
pressure switch contacts and the staggered stopping of the
pumps. An electronic device activates the automatic
rotation of the starting order of the electropumps so as to
ensure uniform distribution of the starting operations, and
therefore of the working hours.
4.1 STANDARDS AND REGULATIONS
The pressure booster sets have been designed and made in
compliance with the following regulations and standards:
• Machines Directive 98/37/EEC
• Low Voltage Directive 73/23/EEC
• Directive on Electromagnetic Compatibility 89/336/EEC
and subsequent updates
• European Standards: EN60204-1; EN60439-1;
EN60335-2-41; EN500081; EN50082; EN809; EN292
4.2 CONSTRUCTION CHARACTERISTICS
The pressure booster sets are supplied complete with:
-electropumps – pressure gauge – pressure switches –
manifold on suction and on delivery – isolating valves on
suction and on delivery – check valve on suction - nipples
on suction with G 1/2 UNI ISO 228 coupling for
connection to an air feeder – various couplings – electric
control panel – single base – vibration-damping supports.
Vertical diaphragm type vessels on delivery are supplied
on request and separately.
Pressure switch kit for minimum pressure on request.
4.3 COMPONENTS
• Depending on type, the electropumps may be singleimpeller,
twin-impeller, multistage with horizontal or
vertical axis. Bodies of cast iron or stainless steel Aisi
304, impellers in technopolymer, cast brass, cast iron,
Aisi 304. Mechanical seal in carbon/ceramic/NBR.
Standard asynchronous electric motors, degree of
protection IP44÷IP55 class F.
• Manifolds: galvanised steel, according to UNI 8863,
threads UNI ISO 228/1, flanges to UNI standards with
rated pressure PN10-PN16.
• Nickel-plated brass interception ball valves
PN10/PN16, seal in PTFE; butterfly valves in painted
cast iron, seal in EPDM.
• Check valves PN10/PN16 spring or flap type, brass
body, NBR rubber seal.
• Couplings PN 25 galvanised cast iron and brass, threads
UNI ISO 7/1.
• Bourdon spring pressure gauges, plastic casing, brass
coupling, scale in bar and in psi.
• Adjustable pressure switches with diaphragm in NBR,
bipolar, silver contacts, plastic casing, protection IP54.
• Base, electric panel supports: galvanised steel.
• Electric panel: plastic or metal casing, protection IP55.
• Nuts and bolts: galvanised steel.
• Components in stainless steel on request.
10 – GP
5. TESTING
Before packing, 100% of pressure booster sets are
subjected to routine hydraulic, mechanical and electric
tests as described in points 5.2 and 5.3.
5.1 CALIBRATING THE PRESSURE SWITCHES
The pressure switches are calibrated (at ambient
temperature) according to the following standard table:
P0 = max pressure of pump n°1 (or pilot pump) with
aperture closed
P1 ÷ P8 = calibrating pressures in bar
∆P = minimum differential in bar
NB: depending on the characteristics of certain types of
pumps (with flat curve), the pressure switch for pump n°1
(or pilot) may be calibrated at a stopping pressure P1= P0
– 0.3 bar
Any diaphragm tanks must be calibrated by the user at a
pressure 0.3÷0.5 bar lower than the starting pressure of the
pressure switch of the last pump (minimum pressure).
Regulating range:
Regulating procedure:
1. Completely slacken the nut or the regulating screw “B”
of pressure switch 1 of pump n°1 (in this way you have
the minimum differential ∆P)
2. Start pump n°1 by means of the manual control (or the
pilot pump when the set is provided with one).
3. Slowly close the isolating valve downstream from the set
until the desired stop pressure (reading on the pressure
gauge), regulate pressure switch n°1 by rotating the nut
or the screw “A” until the contact clicks open, this
operation will stop the pump.
4. Slowly open the isolating valve downstream from the
set, which causes a loss of pressure of the system until
the contact clicks shut on pressure switch n°1(which is
already set with minimum ∆P), this operation will start
the pump. Check regulation by increasing and
decreasing the pressure downstream from the system,
always using the isolating valve.
5. Perform the same operations for the set’s remaining
pressure switches.
6. Discharge the pressure downstream, set automatic
operation on the control panel, slowly open the
isolating valve downstream from the set, check the
cascade intervention calibrations of the pumps at least